Traditionally, bulk cargo unloading has faced challenges around operational efficiency, safety risks, environmental impacts, and high operational costs.
Rough discharges, equipment wear, vibration damage, and limited weather operating windows have all constrained vessel utilisation and performance. Moreover, older unloading systems are energy-intensive and labour-dependent, increasing both costs and environmental footprint.
Cargo unloading systems
Many bulk cargo unloading systems depend on steep slope angles, which limit the types of materials that can be carried efficiently.
MacGregor’s GravityVibe directly addresses this factor by allowing efficient discharge with significantly lower slope angles, thus broadening the range of cargo that can be handled.
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| Many bulk cargo unloading systems depend on steep slope angles. |
Ship structures and unloading equipment
“GravityVibe reduces reliance on gravity alone by augmenting the flow with controlled vibration,” says Mikael Hägglund, Senior Manager, Cranes at MacGregor.
“This approach improves operational efficiency, enhances safety through more predictable material flow, and reduces wear on ship structures and unloading equipment.”
Challenges of space utilisation and cargo versatility
MacGregor is a provider of cargo and load handling solutions to maximise efficiency
Additionally, the GravityVibe system will, in most cases, require only one hold conveyor and no cross conveyor in the hold, making the operations both cost-effective and sustainable, says Hägglund. MacGregor, based in Helsinki, Finland, is a provider of cargo and load handling solutions to maximise efficiency of maritime operations.
As an augmented gravity self-unloading system, GravityVibe enhances cargo flow using vibration, enabling bulk materials to be discharged efficiently at lower slope angles (15–20 degrees). It reduces material blockages and optimises discharge without requiring steep holds, addressing the challenges of space utilisation and cargo versatility.
Mechanical strain on vessel structures
The system lessens mechanical strain on vessel structures, and supports safer, smoother, and more efficient operations across different cargo types.
“Using lower slope angles allows ships to maximise cargo hold volume and transport a wider variety of bulk materials, including those that would not flow well with conventional systems,” says Hägglund. “It improves operational flexibility.”
Integrity of the vessel
Vessels benefit from a more compact and efficient hold design, optimising stability and construction
Structurally, vessels benefit from a more compact and efficient hold design, optimising stability and potentially lowering construction and maintenance costs, adds Hägglund.
“Managing vibration and sound levels is critical for maintaining the structural integrity of the vessel and ensuring crew safety and comfort,” he says. “Excessive vibration can lead to accelerated wear on ship components and fatigue damage over time.”
GravityVibe’s design
GravityVibe’s design ensures that both vibration and sound levels stay well below class-defined thresholds, preserving vessel longevity and reducing long-term maintenance and repair costs.
Bulk cargoes have widely varying properties such as particle size, cohesiveness, moisture content, and chemical reactivity, all of which impact flow behaviour. Sticky, wet, or coarse materials require different unloading strategies to avoid blockages, segregation, or structural strain.
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| Bulk cargoes have widely varying properties like particle size and cohesiveness. |
Broader spectrum of cargo types
Key elements to achieve automation include fine-tuning self-optimisation algorithms
GravityVibe’s vibration-driven approach adapts to these material differences, maintaining consistent discharge rates and ensuring operational reliability across a broader spectrum of cargo types without manual intervention or excessive mechanical modification, says Hägglund.
More automated systems are on the horizon. Fully automated discharge is rapidly approaching reality, thanks to intelligent unloading systems like GravityVibe. Key remaining elements to achieve automation include fine-tuning self-optimisation algorithms, integrating predictive maintenance solutions, and standardising automation interfaces between vessels and ports.
GravityVibe features
MacGregor is actively working to refine onboard software, improve material recognition capabilities, and enhance real-time adjustment features. Wider industry adoption and regulatory frameworks are also crucial for achieving fully autonomous and seamless bulk unloading.
GravityVibe features a built-in self-optimisation system that uses sensors to monitor material flow characteristics during discharge. Based on live data, it automatically adjusts vibration frequency and intensity to match the properties of each specific cargo, ensuring optimal unloading performance without manual recalibration.
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| MacGregor is working to refine onboard software and improve material recognition. |
GravityVibe’s performance
GravityVibe’s performance has been verified through a combination of laboratory studies
MacGregor is fine-tuning this system by gathering real-world data from full-scale test rigs, analysing operational performance across various cargo types, and incorporating feedback loops to continually improve discharge efficiency and system responsiveness.
Real-world validation is essential to prove that unloading systems perform reliably under operational conditions. GravityVibe’s performance has been verified through a combination of laboratory studies and full-scale rig testing.
In-house tests and studies
For example, validation by bulk solids researcher TUNRA showed efficient unloading across diverse materials such as wood chips, manufacturing sand, and gravel.
In-house tests and studies with external specialists like KTH have confirmed low vibration levels, consistent discharge flow, and high operational reliability, providing strong evidence for commercial deployment.
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| TUNRA showed efficient unloading across diverse materials such as sand. |
GravityVibe’s system design
GravityVibe’s system design is based on long-lasting parts and improved cargo flow
High maintenance requirements traditionally have led to significant downtime and increased operational costs. GravityVibe’s system design is based on long-lasting components and improved cargo flow that reduce risks for failures and needed service, thereby lowering maintenance costs/needs.
“With real-time monitoring and smart diagnostics, potential issues can be detected and addressed before they escalate, minimising service interruptions,” says Hägglund. “This proactive approach enhances equipment availability and ensures better operational continuity for vessel operators.”
MacGregor GravityVibe system
When unloading standard bulk carriers, there is a need to clean the holds with manpower and external machines as the port cranes or the vessel cranes will not be able to empty the holds. The weather could also be a factor for delay in cases where the cargo is sensitive to water.
For the MacGregor GravityVibe system, all material will be removed from the hold without any extra efforts. GravityVibe demonstrates that with intelligent use of vibration and lower slope angles can achieve the same — or even better — results. This approach not only enables broader cargo flexibility but also reduces structural stress, energy consumption, and environmental footprint.
